Construction machines such as a hydraulic excavator, a wheel loader, and the like are widely used for work such as gravel or earth digging, road work, farm land consolidation, land creation, water and sewage work, construction foundation work, and the like. In order to carry out the above work with a small number of construction machines, the hydraulic excavator, for example, is interchangeably (that is, attachably and detachably) provided with various kinds of working machine attachments such as various kinds of buckets, a hydraulic breaker, a crusher, and the like. Moreover, a working machine attachment attaching and detaching device called a so-called quick coupler is used to enhance attachment and detachment efficiency.
Although there are various kinds of working machine attachment attaching and detaching devices, the technology described in Japanese Utility Model Bulletin No. 3030543 is the nearest to the present invention. Specifically, as an outline thereof is shown in FIG. 8, "A working machine attachment attaching and detaching device includes a first member 1 and a second member 2. The first member 1, the basic end of which is connected to the forward end of a working machine arm 3 with a first cross-pin P1, is rotatable around the first cross-pin P1 by extension and contraction of a hydraulic cylinder 4. Meanwhile, the second member 2, the basic end of which is connected to the forward end of the first member 1 with a second cross-pin P2, hangs downward. Moreover, with respect to a third cross-pin P3 and a fourth cross-pin P4 each provided in a working machine attachment 5 such as a bucket, breaker, or the like, the first member 1 has a hook 6 with a rotary cap 6a for engaging with the third cross-pin P3 and covering it with the cap near the basic end thereof, and the second member 2 has a hook 7 with a rotary cap 7a for engaging with the fourth cross-pin P4 and covering it with the cap at the forward end thereof." is described.
The above prior art, however, has the following disadvantages.
(1) The hooks 6 and 7 are complicated since they have many parts and mechanisms composing the rotary caps 6a and 7a in narrow spaces. As a result, costs are increased, and durability including rain proof, rust proof, vibration proof, and the like is insufficient for construction equipment which operates in harsh environments. Hence, there is the possibility that the rotary caps 6a and 7a, for example, will not rotate due to rusting, earth and sand caught in the caps, or the like.
(2) The hook 7 opens transversely. Therefore, it is required to previously rotate the second member 2 leftward as illustrated by some means such as manual work or the like and hold it prior to the engagement of the fourth cross-pin P4. Further, in the engagement of the fourth cross-pin P4, it is necessary to rotate the second member 2 by some means such as manual work or the like to engage the fourth cross-pin P4. After all, automatic engagement can not be attained by a share performed by the above manual work. PA1 (3) In the attachment and detachment operation of the working machine attachment 5, generally the operation during engagement (namely, during "attachment") requires more careful handling and more time than the operation during disengagement (namely, during "detachment"). In engagement, as shown in FIG. 9A, with respect to a pin which is engaged first (the third cross-pin P3 in this example) out of the third and fourth pins P3 and P4, the degree of freedom for its alignment is high. Accordingly, even in the conventional method in which the third cross-pin P3 is driven into a pin boss, for example, attachment and detachment efficiency never drops greatly. Meanwhile, as shown in FIG. 9B, with respect to a pin which is engaged later (the fourth cross-pin P4 in this example), the degree of freedom for its alignment is reduced because the third cross-pin P3 is engaged first, thereby making its alignment difficult. Namely, if at least the fourth cross-pin which is engaged later is not easy to align, attachment and detachment efficiency drops greatly. However, the hooks 6 and 7 in the above prior art have the rotary caps 6a and 7a respectively. In the case of the small-sized working machine attachment 5, when the engagement of the third cross-pin P3 engaged first is performed only by manual work, higher attachment and detachment efficiency can be often obtained. In other words, the hooks in the prior art are superfluous and costly for the small-sized working machine attachment 5. PA1 a first member (1) and a second member (2), PA1 the first member (1) the basic end of which is connected to the forward end of a working machine arm (3) with a first cross-pin (P1) being rotatable around the first cross-pin (P1) by extension and contraction of a hydraulic cylinder (4), PA1 the second member (2) the basic end of which is connected to the forward end of the first member (1) with a second cross-pin (P2) hanging downward, and PA1 with respect to a third cross-pin (P3) and a fourth cross-pin (P4) each provided in a working machine attachment (5) such as a bucket, breaker, or the like, the first member (1) being free to engage with the third cross-pin (P3) in the vicinity of the basic end thereof, and the second member (2) being free to engage with the fourth cross-pin (P4) at the forward end thereof, characterized by including PA1 a relationship in which after the engagement of the third cross-pin (P3), the hydraulic cylinder (4) is extended, this extension allowing the fourth cross-pin (P4) to abut on either of the front or rear slant faces (2FF, 2BB) and slide up the same to approach the bottoms of both the recessed portions (8, 8) and at the same time to abut on the lower face of the spindle portion (9u) to boost the same, this boost causing the rotation of the hook (9A) around the fifth cross-pin (P5), this rotation yielding the hook body (9d) to enclose the fourth cross-pin (P4) from the lower sides of both the recessed portions (8, 8), as the result of these boost and enclosure, the fourth cross-pin (P4) being put among the front and the rear slant faces (2FF, 2BB) and the inner face of the hook body (9d), at which time the stop pin (P7) is inserted into the first and second horizontal through-holes (2RH, 2LH, 9H), this insertion permitting the hook (9A) to be fixed to the second member (2), thereby engaging with the fourth cross-pin (P4) at the forward end of the second member (2). PA1 a first member (1) and a second member (2), PA1 the first member (1) the basic end of which is connected to the forward end of a working machine arm (3) with a first cross-pin (P1) being rotatable around the first cross-pin (P1) by extension and contraction of a hydraulic cylinder (4), PA1 the second member (2) the basic end of which is connected to the forward end of the first member (1) with a second cross-pin (P2) hanging downward, and PA1 with respect to a third cross-pin (P3) and a fourth cross-pin (P4) each provided in a working machine attachment (5) such as a bucket, breaker, or the like, the first member (1) being free to engage with the third cross-pin (P3) in the vicinity of the basic end thereof, and the second member (2) being free to engage with the fourth cross-pin (P4) at the forward end thereof, characterized by including PA1 a relationship in which the fourth cross-pin (P4) is located nearly beneath both the recessed portions (8, 8) when the third cross-pin (P3) is engaged near the basic end of the first member (1) while the hook (9B) is mounted on the stop pin (P7), and a relationship in which after the engagement of the third cross-pin (P3), the hydraulic cylinder (4) is extended, this extension allowing the fourth cross-pin (P4) to abut on either of the front or rear slant faces (2FF, 2BB) of both the recessed portions (8, 8) and slide up the same, the stop pin (P7) being pulled out of the first horizontal through-holes (2RH, 2LH) when the fourth cross-pin (P4) abuts on both the front and rear slant faces (2FF, 2BB), thereafter the hook (9B) being rotated around the sixth cross-pin (P6), the stop pin (P7) being reinserted into the first horizontal through-holes (2RH, 2LH) when the inner face of the hook (9B) abuts on the lower face of the fourth cross-pin (P4), and this reinsertion permitting the hook (9B) to be fixed to the second member (2), thereby engaging with the fourth cross-pin (P4) at the forward end of the second member (2).